The present disclosure relates to a time-to-digital converter for digitizing the analog information of the time direction. The present disclosure also relates to an analog-to-digital (A/D) converter for converting an analog signal to the time axis information and converting it into digital form.
The recent finer designs of LSIs have reduced their operating voltages. Thus, the signal processing of the voltage direction is less likely to improve a signal-to-noise (S/N) ratio of the signal. Thus, the signal processing requires the analog quantity of the time axis direction, or the time axis information. This time axis information is an interval between edges of clock signals. This interval, i.e., the phase difference is modulated with an information signal. The system for the signal processing of the time axis information that is superimposed on the clock edges includes the signal processing of the time direction. This system has shorter time for the signal processing with a higher frequency of the clock signals on which the time axis information is superimposed. A typical technique for securing the time for signal processing is to distribute the time axis information signal to parallel systems and process them individually. One example of the known techniques is to distribute the time axis information to individual signal processing systems with a synchronous counter. See, e.g., Non-Patent Document 1.
Non-Patent Document 1: M. Takayama, S. Dosho, N. Takeda, M. Miyahara, and A. Matsuzawa, “A Time-Domain Architecture and Design Method of High Speed A-to-D Converters with Standard Cells,” IEEE Asian Solid-State Circuits Conference, Nov. 14, 2011, pp. 353-356
Non-Patent Document 1 discloses a typical technique for distributing signals with a synchronous counter. The technique requires heavy power consumption. This technique also has considerable difficulty in providing a physical layout of equal-length wiring for distributing the signal to individual signal processing systems.
Therefore, it is necessary to provide a time-to-digital converter operating with low power consumption and having an appropriate physical layout, and an A/D converter including this time-to-digital converter.